Execs at AOL and Verizon hope their merger will be a story for the ages, not a cautionary tale.

An unexpected merger between AOL and a storied incumbent? You'd be forgiven for thinking you'd gone back to the turn of the century, but no, that happened earlier this month. Whatever the reasons behind the AOL-Verizon merger -- for all the talk of AOL's content offerings, its advertising platform may be the big prize -- at a mere $4.4 billion dollars the deal is a pale shadow of the $164 billion blockbuster AOL-Time Warner merger that marked the height of dot-com hubris.

Whether VerAOLzon will fundamentally change the face of the tech business world remains to be seen. But over the years, a number of mergers and acquisitions -- some of which seemed momentous at the time, others barely noticed -- have transformed the industry.

It's interesting to read coverage of Apple's acquisition of NeXT from December 1996, as it primarily focuses on the deal as a vehicle to return Steve Jobs to the fold; you'd think it was a $400 million headhunting trip. In fact, Apple's problems went far beyond the lack of a charismatic leader: its project for a next-generation OS to rival Windows 95, code-named Copland, had been killed in August, and the company desperately needed a way out of the classic Mac OS's dead end. NeXT's Unix-based NeXTSTEP was the company's salvation; OS X, Apple's consumer version of NeXTSTEP, wasn't released until more than four years later, but after a slow start it would power a Mac revival and, in the form of iOS, a consumer product revolution.

In 1984, the U.S. government shattered AT&T's telecom monopoly and broke the company up into a nationwide long-distance company a number of regional phone providers, dubbed "Baby Bells." But like the individual droplets of the liquid metal T1000 in Terminator 2, the severed components of Ma Bell's empire couldn't keep apart. The Northeastern US's providers merged to form Verizon; meanwhile, Texas-based Southwestern Bell gobbled up most of the rest of the country's providers before absorbing its erstwhile parent in 2005 and taking back the AT&T name. While all these mergers went against the spirit of the 1984 breakup, the two behemoths that emerged from the wreckage are now strong enough to survive the decline of landlines and fight in the wireless and data-delivery realms.

It's easy to forget that this most famously ill-starred tech merger took the form not of the established company absorbing a promising upstart, but of AOL leveraging its sky-high stock price to brashly take control of a traditional media giant. But the merger happened in January 2001, at the peak of the market, and as the dot-com bubble burst it became clear that AOL had used its inflated share price to buy a real company that was being dragged down with it. Meanwhile, the Internet-speed synergies promised by the merger never materialized, as execs couldn't get Time Warner's mutually hostile fiefdoms to cooperate. The much-reduced shell of AOL was spun off in 2009.

In 2000, Google figured out a way to make money from its increasingly popular search engine -- AdWords, small text ads that accompanied search results. They were profitable, but the ad industry was unimpressed, calling Google "the ValPak of the Internet." But in 2003, Google acquired Applied Semantics, a company that had pivoted through several ideas before releasing AdSense, a technology that attempted to match relevant ads to the content of the webpages on which they appeared. Google snapped them up, and their ascension to becoming the most powerful company in the advertising industry was rapid.

Unlike many of the acquisitions in this article, this one ended with both companies still standing separately -- but it represented a true milestone, the end of an era. IBM may have invented the PC market as we know it, but by 2004 that had become a low-margin business. By selling its PC division to a Chinese company (despite the geopolitical concerns), IBM acknowledged that the center of gravity for that commodity business had shifted to Asia, where the computers were actually manufactured. The deal also paved the way for IBM to sell its server business to Lenovo a decade later, staking out software and services as the areas where American businesses thrive.

Google's acquisition of little-known mobile startup Android in 2005 was received at the time as just one of a number of moves the company was making to get into the nascent mobile business, along side other non-world-beaters like an SMS search business and Dodgeball, a came-too-soon mobile social network. Android came with Andy Rubin, who had already started and jumped ship from a pioneering Java-based smartphone company called Danger, and while it took a few years to become fully obvious, this acquisition transformed Google from the sort of company that thought SMS search was cool into one of the most important players on the smartphone scene. (Danger, meanwhile, was acquired by Microsoft, a move that led to the disastrous Kin.)

If the HP-Compaq merger at the time seemed to be all about creating the number one PC manufacturer, then the company's acquisition of the Ross Perot-founded Electronic Data Systems just a few years later was an emblem of that transition of American tech companies into the services era that marked the '00s. The merger was considered a success, pushing HP into the higher-end contracts that then-CEO Mark Hurd sought out, even though it, like the Compaq acquisition, was followed by the layoffs of tens of thousands of employees. (A few years later, HP's acquisition of Autonomy, which had similar goals, ended in disaster.)